Cargo or sea containers are commonly used for transporting goods either on land by rail or road transport, or at sea on container ships. Such shipping containers are generally of a rectangular parallelepiped configuration so as to enable the containers to be stacked one on top of the other or to enable the containers to be supported on a deck of a ship or on a tray of a transport vehicle such as a railcar or road vehicle. Shipping containers are usually provided with doors on at least one end to provide access to the interior of the container. Corner fittings or sockets are provided at each external corner of the container for engagement by connecting devices to secure the container to the deck of a ship or tray of a vehicle or to secure containers together. The corner fittings include elongate apertures on the lower side of the container for receipt of rotatable cleats or lugs of the connecting devices which are receivable within the apertures and which are rotatable to lock the containers in position. Apertures are also provided in the corner fittings on the top, side and end faces of the container so that containers stacked upon each other can be locked together or adjacent containers locked together by similar connecting devices in an end-to-end or side-by-side configuration.
A particular difficulty occurs when a shipping container which is on the ground is to be loaded onto a road vehicle having a flat bed or tray, but no crane or hoist to lift the container onto the tray. With this type of vehicle the bed or tray (which is often slidably mounted on the vehicle chassis) is tilted to an inclined position and moved into longitudinal alignment with and adjacent to an end of the container. A winch cable, attached to a winch provided centrally at a front end of the tilt-tray, is coupled to the container. When the winch is operated, the intention is for the container to be drawn onto the tray. However it is not uncommon for the end of the container to abut the rear end of the tray and to become jammed against the rear end of the tray, thereby preventing the container from being winched onto the tray of the vehicle. The result is that a substantial load is then placed on the winch producing high tension in the cable, with the potential for catastrophic failure of either the winch or the cable. If the cable should break it may result in severe injury and even death for any person in the vicinity who may be struck by the cable.
To help avoid this situation and to make it easier to load a container onto a vehicle flat-bed tilt-tray, commonly-owned Australian Patent No 2006900175 describes a method and apparatus for loading containers which involves the use of a specially designed elongated drawbar assembly. The method and apparatus of AU2006900175 has been very successful in overcoming the problems associated with loading a container onto a flat-bed tray. However there are also problems associated with the reverse process of unloading a container from a flat-bed tray. For example, when the container is ready to be unloaded, the gravitational forces acting on the container by tilting the tray may not be sufficient to overcome the frictional forces between the bottom of the container and the tray. There is a risk that the container may slide backwards off the tray in an uncontrolled manner.
The present invention was developed with a view to providing a system and method of both loading and unloading a shipping container more safely from a flat-bed tray. The invention also relates to an ejector assembly for assisting in unloading a shipping container from a vehicle tray, and relates more particularly to a vehicle with a tilt-tray which is fitted with such an ejector assembly.
References to prior art in this specification are provided for illustrative purposes only and are not to be taken as an admission that such prior art is part of the common general knowledge in Australia or elsewhere.